The present invention relates to a centralizer segment and a centralizer formed of one or more centralizer segments.
The centralizer may be used to centralise a borehole casing. Such borehole casings may be used, for example, in water wells, oil wells and gas wells.
In accordance with one aspect of the present invention, there is provided a centralizer segment 200 comprising a first collar portion 202, a second collar portion 204, bow means 206 extending between said first collar portion 202 and said second collar portion 204, first connection means 208 provided at first locations of said first collar portion 202 and said second collar portion 204, respectively, second connection means 210 provided at second locations of said first collar portion 202 and said second collar portion 204, respectively, wherein said first connection means 208 are engagable with said second connection means 210 of the same or another centralizer segment 200 such that one or more said centralizer segments 200 are connectable together to form a centralizer around a borehole casing.
Preferably, said first and second connection means 210 allow the relative positional engagement between said first and second connection means 208, 210 to be selected.
Preferably, said first connection means 208 comprises teeth provided on said first and second collar portions 202, 204 on a first face of said centralizer segment 200 and said second connection means 210 comprises pawl means provided on said first and second collar portions 202, 204 on a second face of said centralizer segment 200.
Preferably said second connection means 210 further comprises guide means for receiving first and second collar portions 202, 204 of a said centralizer segment 200.
Preferably, said first and second collar portions 202, 204 are provided with lug members on a face of said centralizer segment 200 that, in use, faces away from the borehole casing.
The lug members can be used to tighten the centralizer segment 200 around the borehole casing.
Preferably, said bow means 206 is flexibly resilient.
Preferably, said bow means 206 is curved in the direction between said first and second collar portions 202, 204.
Preferably, said bow means 206 extends between said first and second collar portions 202, 204 intermediate the locations of said first and second connection means 208, 210.
Preferably, agitation promoting means is provided on said centralizer segment 200 to promote agitation of grout injected into a borehole.
Preferably, said agitation promoting means comprise rib members provided on said bow means 206.
Preferably, said rib members are provided on a face of said centralizer segment 200 that, in use, faces the borehole casing.
Preferably, at least one of said rib members is provided with at least one enlarged portion.
Preferably, said bow means 206 comprises at least two strap members extending between said first and second collar portions 202, 204.
Preferably, said first and second collar portions 202, 204 are substantially parallel.
Preferably, said first and second collar portions 202, 204 are provided as strap members.
Preferably, said centralizer segment 200 is made of a corrosion resistant material.
In accordance with a second aspect of the present invention, there is provided a centralizer for a borehole casing comprising a centralizer segment 200, as hereinbefore described, connected together via said first and second connection means 208, 210 around a borehole casing.
The centralizer may comprise at least two centralizer segments 200 connected together via said first and second connection means 208, 210 around a borehole casing.
In accordance with a third aspect of the present invention, there is provided a centralizer for a borehole casing comprising at least two centralizer segments, 200 as hereinbefore described, connected together via said first and second connection means 208, 210 around a borehole casing.